Reinforced core bullet

ABSTRACT

A jacketed bullet has a core of a dense metal or metal alloy, an inner jacket at least partially surrounding and bonded to the core; and an outer jacket at least partially surrounding the inner jacket and core.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/505,177, filed Jul. 17, 2009, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/083,651, filed Jul. 25, 2008.The disclosures of both above-referenced applications are incorporatedherein by reference.

FIELD

The present disclosure relates to improvements in bullets, and inparticular, to an improved bullet with a reinforced core.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure, and may not constitute prior art.

Considerable effort is devoted to the design of bullets to improve theirperformance. These efforts include designs to improve mass retention ofthe bullet after it strikes its target, to maximize the impact of thebullet on the target. These efforts also include designs to improveexpansion of the bullet after it strikes its target, to maximize damageto the target. Despite these efforts, improvements are still needed, inparticular, to maintain bullet performance at higher bullet velocities.

SUMMARY

Generally, embodiments of this invention provide an improved bullet witha reinforced core, and methods of making such bullets. In a preferredembodiment, the bullet comprises a core of a dense metal or metal alloy.An inner jacket at least partially surrounds and is bonded to the core.An outer jacket at least partially surrounds the inner jacket and core.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a longitudinal cross-sectional view of a preferred embodimentof a bullet constructed according to the principles of this invention;

FIG. 2 is photographic longitudinal cross section of a preferredembodiment of a bullet constructed according to the principles of thisinvention;

FIG. 3 is a photographic perspective view of the reinforced core of thebullet of the preferred embodiment;

FIG. 4 is a photographic perspective view of the outer jacket of thebullet of the preferred embodiment;

FIGS. 5A and 5B are photographic top plan and top perspective views ofthe manufacture of the bullet of the preferred embodiment, showing thebullet after the nose cavity is formed in the front end;

FIGS. 6A and 6B are photographic top plan and top perspective views ofthe manufacture of the bullet of the preferred embodiment, showing thebullet after the lines of weakness are formed in the front ends of thejackets;

FIGS. 7A and 7B are photographic top plan and top perspective views ofthe manufacture of the bullet of the preferred embodiment, showing thebullet after the nose cavity and ogival taper is formed;

FIG. 8 is a photographic rear plan view of an upset of the bullet of thepreferred embodiment;

FIG. 9 is a photographic side elevation view of an upset of a bullet ofthe preferred embodiment;

FIG. 10 is a photographic rear perspective view of an upset of a bulletof the preferred embodiment;

FIG. 11 is a longitudinal cross-sectional view of a pre-formedcup-shaped outer jacket used in an alternate preferred embodiment;

FIG. 12 is a longitudinal cross-sectional view of a pre-formedcup-shaped outer jacket used in an alternate preferred embodiment;

FIG. 13 is a longitudinal cross-sectional view of a pre-formedcup-shaped outer jacket used in an alternate preferred embodiment;

FIG. 14 is a longitudinal cross-sectional photograph of a bullet madeaccording to the alternate preferred embodiment;

FIG. 15A is a photograph of a bullet made according to the preferredembodiment of this invention, after being fired into gelatin at avelocity of 1650 fps; and

FIG. 15B is a photograph of a bullet made according to the alternatepreferred embodiment of this invention, after being fired into gelatinat a velocity of 1650 fps.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

A preferred embodiment of a bullet with a reinforced core in accordancewith the principles of this invention is indicated generally as 20 inthe Figures. Bullet 20 has an ogival tapered nose portion 22 at thefront end and a heel 24 at the opposite end. The bullet 20 preferablyhas a hollow point 26, with a plurality of lines of weakness 28 so thatthe bullet can expand upon impact with the target, as shown in FIG. 1,the bullet 20 comprises an outer jacket 30 and a reinforced core 32. Thereinforced core 32 comprises a relatively soft, dense inner core body34, and an inner jacket 36.

The inner core body 34 is preferably made of lead or a lead alloy.However, the inner core body 34 could be some other dense metal ormaterial. Because of environmental concerns, for at least someapplications, the inner core body 34 can be lead-free, for examplecomprising tin, tin alloys, tungsten, or tungsten alloys.

The inner jacket 36 is preferably made of copper or a copper alloy. Theinner jacket 36 preferably comprises a drawn copper cup 38 in which apre-formed inner core body 34 is bonded (FIG. 3). In the preferredembodiment, the inner core body 34 and inner jacket 36 are heated tobond them together. The inner core body 34 could alternatively be bondedin the inner jacket 36 with a bonding agent, for example an adhesivesuch as an epoxy. Alternatively, the inner core body 34 could be cast inthe inner jacket 36. In still another alternative, the inner jacket 36could be applied over the core 26, for example by chemical plating orelectroplating.

The outer jacket 30 is preferably made of copper or a copper alloy. Theouter jacket 30 is preferably a drawn cup 40 (FIG. 4) into which thereinforced core 24 is inserted and bonded. Forming the outer jacket 30from a drawn copper or copper alloy cup allows the thickness of thewalls of the outer jacket 30 to be varied along the length of the bullet20. In the preferred embodiment, the portions of the outer jacket 30adjacent the front 22 of the bullet 20 are thicker than the portions ofthe outer jacket adjacent the heel 24 of the bullet. The thickness, andthe rate of change or taper of the outer jacket 30 can be controlled toadjust the performance of the bullet 22 on impact, for example to changethe bullet's performance at a given velocity, or to change the bullet'sperformance relative to a given barrier (target) type, or to change thedegree of expansion upon impact.

The lines of weakness 28 allow the portion of the outer jacket 30 overthe front portion 22 of the bullet 20 to expand and form a plurality ofpetals 42 (FIGS. 8-10). Each of the petals 42 preferably has a bend 44,formed by the portion of the jacket 30 in the hollow of the hollow nose26, with a point 46 at the end of the petal 42.

The lines of weakness 28 also allow the inner jacket 36 to expand andform a plurality of petals 48, which are generally aligned with thepetals 42. Like petals 42, petals 48 each have a bend 50 therein,corresponding to the portion of the jacket at the front 22 of thebullet, and a point 52. Because the inner jacket 36 is bonded to theinner core body 34, the petals 48 pull material from the inner core body34 with them as they expand. Thus the petals 48 tend not to expand asmuch as the petals 42, so that their points 52 are offset from thepoints 46. Furthermore, the petals 48 tend to protect the petals 42,preventing them from expanding too far and/or tearing off.

The bullet 20 is preferably fabricated by inserting a pre-formed innercore body 34 into a pre-formed cup 38 that is the precursor of the innerjacket 36. The inner core body 34 and cup 38 are heated to bond theinner core body 34 in the cup 38, indicated generally as 54 in FIG. 3.The core and cup combination 54 is inserted into a cup 40, which is theprecursor of the outer jacket 30 (shown in FIG. 4), with the closed endsof the cups 38 and 40 oriented in the same direction. The walls of thecup 40 preferably have a varying tapered configuration, being generallythicker at the closed end 56 (which forms the front 22 of the bullet20), and thinner at the open end 58 (which forms the tail 24 of thebullet). The profile of the cup 40 is designed to provide the desiredwall thickness for the jacket 30. For example, as shown in FIG. 1, thethickness of the jacket 30 is generally greatest at the front 22 of thebullet 20, and thinnest at the tail 24. More specifically, as shown inFIG. 1, the portion 30 a of the jacket 32 adjacent the bottom of therecess 26 tapers toward the bottom of the recess. The portions 30 b and30 c at the front end of the bullet on the inside and outside,respectively, of the recess 26 are generally of constant thickness andrelatively thick. This thickness allows the bullet to be fired at higherspeeds without over expansion. The portion 30 d of the jacket 32 on theside of the bullet tapers toward the heel 28. Finally, the portion 30 eadjacent the heel 24 is relatively thin.

The core and cup combination 54 and the cup 40 are compressed in a die,which simultaneously forms a frustoconical depression 60 in the closedends of the cups 38 and 40, mechanically bonds the cups and thus, theinner and outer jackets 30 and 36, and wraps the open ends of the cupsaround the back end of the inner core body 34. The bullet after thisoperation is shown in FIGS. 5A and 5B. As part of this operation, a discof copper or copper alloy (or some other metal) can be inserted into theopen end of the cup 38 and/or the cup 40, so that as the cups arewrapped around the heel of the bullet, the disc is secured, closing theopen end of the bullet.

In the next step, the bullet is pressed in a die to form score lines 62in the frustoconical depression 60 in the closed ends of the cups 38 and40, which form the lines of weakness 28 in the outer jacket 30 and theinner jacket 36. The bullet after this operation is shown in FIGS. 6Aand 6B. In the preferred embodiment there are six score lines 62 thatare equally spaced to form lines of weakness 28 that form petals ofequal size. However, there could be fewer or more score lines, and theirspacing could be varied to form a different number of petals, and/orpetals of more than one size.

In the next step, the bullet is pressed in a die to form the ogivaltaper in the front 22 end of the bullet. The bullet after this operationis shown in FIGS. 7A and 7B.

The resulting bullet 20 is adapted to be fired at higher speeds, becauseof the reinforced core 32 (specifically the bonded inner jacket 26), andthe thicker outer jacket 30. The outer jacket 30 opens into a pluralityof pointed petals 42 that damage the target. The inner jacket 36similarly opens into petals 48, which because of the bonding with theinner core body 34, pull core material with them. This helps reinforcethe petals 42 of the outer jacket, and provides a second set of pointedpetals 48. Because of the bonding between the inner core body 34 and theinner jacket 26, the bullet 20 retains substantially all of its weight.

The material from which each of the cups 38 and 40 (and thus each of thejackets 30 and 36) is made, could be the same, but they could bedifferent, to provide different mechanical properties to the bullet 20.The materials can also be different, or treated differently (for exampleby surface treatment, oxide coating, plating, polishing, etc.) to imparta unique appearance to the bullet (particularly in its upset or firedstate). Thus, the colors of the inner jacket 36 and the outer jacket 30can be different, so that the petals 42 and 48 have different colors, orare otherwise visually different. For example the cup 38 could be madeof, or the interior could be plated with, a brass-colored metal alloy,while the cup 40 could be made of, or the interior could be plated witha copper-colored metal alloy. Alternatively, one of the cups could bemade of, or plated with, a silver-colored alloy. While it isparticularly desirable that the visible surfaces of the petals 42 and 48(which correspond to the inside of the cups 38 and 40) contrast, theexteriors of the cups 38 and 40 could alternatively or additionally beprovided with a contrasting appearance as well.

In an alternate preferred embodiment, at least one of the cup 38 or 40can formed with at least mechanical retainer to facilitate engagementbetween the inner and outer jackets 30 and 36. This helps preventseparation of the inner and outer jackets 30 and 36, particularly duringhigh velocity impacts, thereby preserving bullet mass.

Thus in accordance with a first alternate preferred embodiment, analternative cup 40′ is used, which is provided with a shoulder 64 formedtherein. Thus, when the core and cup combination 54 and the cup 40′ arecompressed in a die, the shoulder 64 forms a corresponding matingshoulder 66 in the outer surface of the core and cup combination 54. Themating shoulders 64 and 66 help retain the inner jacket and core in theouter jacket when the bullet strikes a target, and the petals on theouter jacket open. Thus, the bullet retains more of its mass.

While the shoulder 64 can be formed perpendicular to the axis of the cup40′, such as by machining, this would be difficult, time consuming, andexpensive. Thus, as shown in FIGS. 11 and 12, the shoulder 64 ispreferably a tapering region formed in the sidewall of the cup 40′. Theangle of the taper depends upon the construction of the bullet and thespeeds at which it will hit a target but the inventors have found thatangles as low as 10° can improve retaining the inner jacket 36 in theouter jacket 30. Preferably, the angle of taper is between about 15 andabout 20 degrees, which can be conveniently formed as part of thedrawings process of making the cup 40′. Of course more than one shouldercan be provided. Thus, in FIG. 13, a cup 40″ having two shoulders 64Aand 64B is provided.

The shoulders face away from the front of the bullet, and are preferablyspaced sufficiently from the front of the jackets 36 and 30, that theydo not interfere with the cuts that for the petals. In the cup 40′ shownin FIG. 11, the shoulder 64 begins about 0.594 inches (about 66.7% ofthe length) from the closed end of the cup. The shoulder 64 tapers froma diameter of about 0.415 inches to diameter of about 0.3995 inches, atan angle of about 20°. This corresponds to about a 3.9% increase indiameter at the shoulder 64. In the cup 40′ shown in FIG. 12, theshoulder 64 begins about 0.601 inches (about 67.5% of the length) fromthe closed end of the cup to the front of the cup. The shoulder 64tapers from a diameter of 0.415 inches at an angle of about 15°. Thiscorresponds to about a 3.9% increase in diameter at the shoulder 64. Inthe cup 40″ shown in FIG. 13, there are two shoulders 64A and 64B. Theshoulder 64A begins about 0.586 inches (about 65.8% of the length) fromthe closed end of the cup. The shoulder 64A tapers from a diameter ofabout 0.415 inches to diameter of about 0.3995 inches, at an angle ofabout 10°. This corresponds to about a 3.9% increase in diameter at theshoulder 64A. The shoulder 64B begins about 0.631 inches (about 70.8% ofthe length) from the closed end of the cup. The shoulder 64B tapers froma diameter of about 0.425 inches to diameter of about 0.415 inches, atan angle of about 15°. This corresponds to about a 2.4% increase indiameter at the shoulder 64B, and an overall increase of about 6.4% overshoulders 64A and 64B.

The shoulders of this preferred embodiment are preferably spaced about0.5 to 0.7 inches from the end of the cup. They provide a change indiameter of at least about 2%. The shoulder preferably has an angle ofat least about 10°, and more preferably between about 15° and about 20°.

As shown in FIG. 14 the shoulder forms a mechanical interference betweenthe jackets, helping to retain them together. Of course, instead of, orin addition to the shoulder 64 on the inside of the cup 40′ or 40″, ashoulder could be formed on the outside of the cup 38, however itappears that it is more convenient to form the shoulder in the cup 40.

FIGS. 15A and 15B illustrate the difference between a bullet with theshoulder 64, and a bullet without the shoulder 64 when they strikeballistic gelatin at a speed of approximately 1650 fps. The bullet inFIG. 15A separated into two principal parts, but the bullet FIG. 15B didnot separate, and thus retained its mass and was more effective for itsintended purpose.

1. A jacketed bullet comprising: a core of a dense metal or metal alloy;an inner jacket at least partially surrounding and bonded to thematerial of the core; and an outer jacket at least partially surroundingthe inner jacket and core.
 2. The jacketed bullet according to claim 1wherein the inner jacket has a thickness of between about 0.005 inchesand 0.02 inches.
 3. The jacketed bullet according to claim 1 wherein theouter jacket is thicker than the inner jacket.
 4. The jacketed bulletaccording to claim 1 wherein the bond between the material of the coreand in the inner jacket is formed by at least partially melting apre-formed core in a pre-formed inner jacket.
 5. The jacketed bulletaccording to claim 1 wherein the inner jacket and the outer jacket havelongitudinally extending lines of weakness that can separate on impactto form petals.
 6. The jacketed bullet according to claim 5 wherein thelines of weakness in the inner jacket and the outer jacket are aligned,so that the petals formed by the jackets on impact are generallyaligned.
 7. The jacketed bullet according to claim 5 wherein the linesof weakness are formed by areas of thinness in the inner and outerjackets.
 8. The jacketed bullet according to claim 5 wherein the linesof weakness are formed by cuts through the inner and outer jackets. 9.The jacketed bullet according to claim 1 wherein the outer jacket doesnot upset upon impact in 20% ballistic gelatin at an initial velocity of1200 fps or less.
 10. The jacketed bullet according to claim 1 whereinthe bullet retains at least 99% mass when fired at an initial velocityof 1800 fps or less at 20% ballistic gelatin.
 11. The jacketed bulletaccording to claim 1 further comprising a mechanical engagement betweenthe inner jacket and the outer jacket.
 12. The jacketed bullet accordingto claim 11 wherein the mechanical engagement between the inner jacketresults from a shoulder pre-formed in at least one of the outer jacketand the inner jacket.
 13. The jacketed bullet according to claim 12wherein the mechanical engagement between the inner jacket and the outerjacket results form a shoulder pre-formed in the outer jacket, and acorresponding deformation in the inner jacket.
 14. An improved jacketedbullet of the type comprising a core of a dense metal or metal alloy,and a jacket bonded to the material of the core, the improvementcomprising a second jacket disposed over the core and the bonded jacket.15. A jacketed bullet comprising: a core of a dense metal or metalalloy; an inner jacket at least partially surrounding and bonded to thematerial of the core, the inner jacket having generally longitudinallyextending lines of weakness therein so that the inner jacket formspetals upon impact; and an outer jacket at least partially surroundingthe inner jacket and core, the outer jacket being thicker than the innerjacket, and having lines of weakness therein so that the outer jacketforms petals upon impact. 16.-18. (canceled)
 19. The jacketed bulletaccording to claim 1 wherein the bond between the material of the coreand in the inner jacket is formed by casting the core in a pre-formedinner jacket.
 20. The jacketed bullet according to claim 1 wherein thebond between the material of the core and the inner jacket is formed bya bonding agent.
 21. The jacketed bullet according to claim 1 whereinthe inner jacket is made of copper or a copper alloy.
 22. The jacketedbullet according to claim 21 wherein the outer jacket is made of copperor a copper alloy.
 23. The jacketed bullet according to claim 1 whereinthe bullet has a generally cylindrical rearward portion, and a taperingforward portion, and wherein the portion of the outer jacket over thetapering forward portion had a generally constant thickness, and theportion of the outer jacket over the generally cylindrical rearwardportion tapers in thickness toward the rearward end of the bullet.